JP5080550B2 - Autonomic nerve function evaluation device - Google Patents

Description

  The present invention relates to an autonomic nervous function evaluation apparatus using a pulse wave analysis method.

  Conventionally, in order to evaluate the autonomic nervous function due to heartbeat variability with a quantitative index, an evaluation method based solely on measurement by an electrocardiograph has been carried out as a non-invasive and simple method. Autonomic nerve function determination based on this electrocardiogram recording is often determined at 100 beats, 150 beats, and 2 minutes. In this case, it is common to obtain a coefficient of variation of the RR interval of the electrocardiogram and make a clinical diagnosis with reference to “normal values” by age. However, the so-called “normal value” is not a universal value, but is uniquely determined by each medical institution with reference to the values in the literature.

  Heart rate variability is affected by aging, and its coefficient of variation decreases with aging. This is clear from Table 1 showing the heart rate variability coefficients reported so far.

  It is said that there is no gender difference in the “normal value” of the heart rate variability coefficient. In addition, it is reported that although the daytime heart rate variability coefficient is low and the night time heart rate variability coefficient is high, the intraday variability is within 2%, there is no significant difference and there is no influence on the judgment. (For example, refer nonpatent literature 1). Moreover, it is thought that the fall of heart rate variability reflects the abnormality of an autonomic nerve function, especially the parasympathetic nerve function fall. This abnormality in autonomic nerve function is an abnormality in the balance between sympathetic nerve function and parasympathetic nerve function.

  For example, diabetic patients often have autonomic neuropathy such as dysfunction of the digestive tract, dysuria, and orthostatic hypotension, as well as somatic neuropathy such as numbness, attenuation or disappearance of the Achilles tendon reflex, and vibration dysfunction. Even in patients without such autonomic symptoms, the heart rate variability coefficient of the ECG RR interval is often decreased (for example, see Non-Patent Document 2). Moreover, the heart rate variability coefficient is also reduced in some cerebral infarction patients and patients with neurological diseases (for example, see Non-Patent Document 3). Such abnormal autonomic nervous function leads to instability of circulatory dynamics and increases the risk of complications.

  In addition, measurement of heart rate variability using pulse waves is also experimentally performed. For example, a pulse wave that extracts velocity pulse waves obtained by differentiating a detected volume pulse wave to extract information corresponding to the RR interval of the electrocardiogram. An analysis method is known (see, for example, Patent Document 1). However, the measurement of heart rate variability due to pulse waves has not yet been put to practical use in the medical field.

  Pulse pressure is the difference between systolic blood pressure and diastolic blood pressure, which is a function of stroke volume and arterial compliance. The pulse pressure waveform changes as it goes from the aorta to the peripheral artery. This is thought to be due to the fact that the projected wave and the reflected wave are synthesized at various sites and resonance occurs, and the degree of transformation can be considered as the sum of the effects of the properties or characteristics of the blood vessels. Comparing the intra-arterial pressures in the aorta and peripheral arteries, the mean arterial pressure and diastolic blood pressure in the peripheral arteries are lower than in the aorta. However, the systolic blood pressure becomes higher in the peripheral artery due to the synthesis of the projection wave and the reflected wave, and thus a phenomenon occurs in which the pulse pressure increases. Therefore, the peripheral pulse waveform has an advantage that the corrugations are larger than the central pulse wave and the waveform can be easily discriminated. Even so, the baseline of the original waveform may not be stable and it may be difficult to recognize the inflection point.

Therefore, the acceleration pulse wave, which is the second derivative wave obtained by differentiating the original waveform of the volume pulse wave, which is the peripheral pulse wave measured with the fingertip, is used in research and clinical practice as a waveform more suitable for evaluation. Yes. At present, the most popular pulse wave meter is a photoelectric fingertip plethysmograph. The principle of this sphygmomanometer is based on a method of obtaining a waveform by applying light having a wavelength specific to light absorption to hemoglobin to the fingertip, and determining the volume change of blood flow in the blood vessel from the absorbed light or reflected light. . The volume pulse wave and the pressure pulse wave are different from each other, but the meanings of the waveforms are the same.
As for the physiological activities (autonomic nerve function, etc.) that the acceleration pulse wave of the peripheral pulse wave expresses in the living body, it is known about the study of the correspondence between the change of the average waveform and the autonomic nerve function. However, there is no known study that examined the correspondence between changes in individual component waves and autonomic nervous function.

  The acceleration pulse wave is a waveform at the systole of the heart and has five component waves of a to e waves (FIG. 1). These component waves change according to the condition of the living body and according to aging. The component wave (a wave) having the apex a corresponds to the waveform of the rising portion of the original waveform, and the component wave (e wave) having the apex e corresponds to the notch portion of the original waveform at the end of contraction. Therefore, at the time of extrasystole or tachycardia, the ae interval is shortened and each component wave is also deformed. When the upper side of the waveform has a positive quadrant and the lower side has a negative quadrant, the a wave is a positive wave that is always above the base line, and the b wave is a negative wave that is always below the base line. The d wave and the e wave are component waves that change to positive or negative depending on the condition of the living body.

  Further, since the waveform of the acceleration pulse wave changes with aging, it is difficult to discriminate between physiological changes and pathological changes. In order to correctly evaluate different waveforms depending on the measurement instrument, measurement environment, age, etc., it is necessary to establish a common waveform evaluation method that can be adapted to any conditions. In other words, if the measurement environment is the same, it is necessary to create a common standard that can be used in common for any instrument and any age group, and it is necessary to evaluate based on that. Not established.

JP 2001-70265 A (Claims)

Shigeru Kageyama et al .: ECG RR interval fluctuation, Internal Medicine, 55: 242-246 (1985) Bernardi L., Ricordi L., Lazzari P. et al: Impaired circadian modulation of simpathetic activity in diabetes, Circulation, 1992; 86: 1443-1452 Masakazu Miyata, Tatsuo Matsuura: CVR-R, Psychosomatic Medicine, Vol. 3, No. 8 1991

  The basis of heart rate variability measurement as an evaluation of autonomic nervous activity is a change in the generation interval of electrocardiographic pulses that is the cause of heart beat. In particular, the R wave interval (RR interval) representing the onset of ventricular contraction is evaluated. However, measurement with an electrocardiograph is not simple. In particular, unlike measurement using a thermometer or blood pressure monitor, it is not possible for a patient to measure at home and see the progress. Therefore, development of an autonomic nervous function evaluation apparatus for use in the implementation of a simple method for evaluating the autonomic function by obtaining the coefficient of variation of the RR interval of the electrocardiogram as described above is required.

  In addition, when trying to evaluate autonomic nerve function using volume pulse velocity or velocity pulse wave instead of coefficient of variation of RR interval of electrocardiogram, pulse misdiagnosis or detection error due to baseline fluctuation or body motion noise may occur. There is also a problem that determination is difficult particularly when the pulse is small.

  Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and is not based on an electrocardiogram, but an acceleration pulse wave analysis method for evaluating an autonomic nerve function or the like using an acceleration pulse wave It is in providing the autonomic-nervous function evaluation apparatus which utilizes A.

  The autonomic nervous function evaluation apparatus according to the present invention for analyzing fluctuations in acceleration pulse wave detects pulse waves of a living body and outputs a signal corresponding to the magnitude of the pulse wave, and obtains the pulse wave measurement means. Waveform parameter analyzing means for analyzing the waveform parameter from the waveform of the acceleration pulse wave calculated by second-order differentiation of the waveform of the obtained pulse wave, and the waveform parameter analyzing means measured continuously for a predetermined time Means for secondarily differentiating the waveform of the pulse wave to calculate an acceleration pulse wave, and means for obtaining a change in the aa interval corresponding to the change in the RR interval of the electrocardiogram from the continuous waveform of the acceleration pulse wave; In addition, with regard to aa intervals excluding those in which changes in adjacent aa intervals are outside a certain range, these values constitute a standard aa interval, and an abnormality in the aa interval is determined. It has the means to do.

  The autonomic nervous function evaluation apparatus is a pulse wave analysis method for obtaining information corresponding to fluctuations in the RR interval of an electrocardiogram from a pulse wave of a living body, and secondarily calculates a pulse wave waveform measured continuously for a predetermined time. The acceleration pulse wave is calculated by differentiation, the aa interval is obtained from the continuous waveform of the acceleration pulse wave, and the change in the aa interval is set as the interval corresponding to the change in the RR interval of the electrocardiogram. In the pulse wave analysis method described above, the standard aa interval is constituted by these values with respect to the aa interval excluding those in which the change in the adjacent aa interval is out of a certain range, and the aa interval is abnormal. Can be used to implement a pulse wave analysis method.

  According to the present invention, the aa interval is obtained from the continuous waveform of the acceleration pulse wave calculated by second-order differentiation of the waveform of the biological pulse wave measured continuously for a predetermined time, and the fluctuation of the aa interval is obtained. Corresponds to the change in the RR interval of the electrocardiogram, so that the evaluation of the variability of the aa interval can be used for the evaluation of the autonomic nervous function as the evaluation of the heart rate variability by the electrocardiogram. Play. According to the present invention, long-time continuous measurement and detection of extra-systolic waves are possible.

  Moreover, since the power spectrum of the aa interval variation after the extrasystole correction, which has not been possible with the conventional methods using an electrocardiograph, can be calculated, there is an advantage that the range of clinical application is widened.

  Furthermore, the acceleration pulse wave measurement is simpler than the case of an electrocardiogram because it only measures the pulse wave of the fingertip in the sitting position without attaching / detaching clothes. Furthermore, the acceleration pulse wave measuring device is less expensive than the electrocardiograph.

  Therefore, according to the present invention, in various fields such as diabetes, neuropathy, cerebrovascular disease, coronary artery disease, asthma, climacteric disorder, it can be widely used for prediction of complication risk, determination of therapeutic effect, self-management and the like. .

FIG. 4 is a waveform diagram of a cardiac systole, which is a standard waveform of an acceleration pulse wave having five component waves of a, b, c, d, and e waves. The waveform figure of the volume pulse wave, velocity pulse wave (primary differential wave), and acceleration pulse wave (secondary differential wave) which were measured and recorded using the pulse wave sensor. The wave form diagram which shows the waveform which measured the electrocardiogram (ECG) and the acceleration pulse wave (APG) simultaneously. The graph which shows the relationship between the aa space | interval of the acceleration pulse wave measured simultaneously, and the RR space | interval of an electrocardiogram. Flow chart of acceleration pulse wave analysis. The graph for demonstrating the similarity determination by the integration (difference integration) of the pulse height difference of an acceleration pulse wave. The graph for demonstrating the flow of an aa space | interval redetermination process. The graph which shows the relationship of the aa space | interval (msec) with respect to the number of beats for demonstrating abnormal value determination of an aa space | interval. The graph which shows the relationship of the aa space | interval (msec) with respect to the number of beats for demonstrating that there is a case where an abnormal aa space | interval is not detected if the normal range is determined from the whole Taa distribution. The graph for showing the relationship of the aa interval (msec) with respect to the number of beats, for explaining a case where the simple transition average does not work. The graph which shows the relationship of the aa space | interval (msec) with respect to a beat number by comparing a transition average and a standard aa space | interval regarding abnormal value determination of an aa space | interval. The graph which shows the relationship between the average value of the variation coefficient (CVaa%) of the aa space | interval of the acceleration pulse wave about a healthy person, and a standard deviation. The graph which shows the range of the standard variation coefficient in each age shown in FIG. 12 as [average value-standard deviation]-[average value + standard deviation]. The graph which shows the variation coefficient of the aa space | interval of the acceleration pulse wave of a diabetic patient compared with the case of a healthy person. It is sectional drawing which shows the structure of the pulse wave sensor which can be used by this invention, (a) is sectional drawing which shows the typical structure of the finger mounting part which is the principal part of this pulse wave sensor, (b) is FIG. The expanded sectional view of the vicinity of the light emission part and light reception part of (a). It is a schematic diagram which shows the directivity of light, (a) is a figure which shows the influence of the directivity of the light emitting element and light receiving element in a prior art, (b) is the directivity of the light emitting element and light receiving element in this invention. The figure which shows about an influence. Sectional drawing which shows the typical structure of the periphery of the insulator cap which has a collar part in another pulse wave sensor which can be used by this invention. It is sectional drawing which shows the structure of another pulse wave sensor which can be used by this invention, (a) is sectional drawing which shows the typical structure of the finger | toe mounting part which is the principal part of this pulse wave sensor, (b). (A) The expanded sectional view of the vicinity of the light emission part and light reception part of (a).

  According to the present invention, it is possible to analyze fluctuations in acceleration pulse waves, evaluate autonomic nerve functions and the like based on the fluctuation analysis, and perform various medical diagnoses and health examinations. This variation analysis is performed based on a measurement / detection result of a pulse wave sensor used by being attached to a fingertip of a living body. The pulse wave measuring device including the pulse wave sensor has a microcomputer in which a pulse wave analysis program for extracting an aa interval from predetermined acceleration pulse wave information is incorporated.

  Fig. 2 shows volume pulse velocity, velocity pulse wave (first differential wave), and acceleration pulse wave (second differential wave) measured and recorded using a pulse wave sensor (ARTETT (registered trademark) manufactured by Yumedica Co., Ltd.). Show. As shown in FIG. 1, this acceleration pulse wave has five component waves of a wave, b wave, c wave, d wave, and e wave. The acceleration pulse wave composed of these five component waves is a cardiac systolic wave, and these component waves change according to the state of the living body and according to aging. However, the e wave is a boundary wave between contraction and expansion. In addition, by using this pulse wave sensor for measurement, it is possible to obtain continuous waveform data that suppresses generation of noise due to body movements as much as possible.

  FIG. 3 shows waveforms obtained by simultaneously measuring an electrocardiogram (ECG) and an acceleration pulse wave (APG). As is apparent from FIG. 3, the a wave of the acceleration pulse wave appears with a certain time delay (α) in the appearance of the electrocardiogram R wave. At this time, the aa interval (APG / aa interval (Taa)) of the acceleration pulse wave substantially coincides with the RR interval (ECG / RR interval) of the electrocardiogram (FIG. 4).

[Measurement of acceleration pulse wave a-a interval and calculation of coefficient of variation]
According to the knowledge of the present inventors, acceleration pulse wave waveform evaluation for evaluating the degree of aging of blood vessels is performed in 10 periods during which the volume pulse wave is stable in a measurement period from about 10 seconds to about 20 seconds. It was enough if the beat level could be detected. However, in order to evaluate the autonomic nervous function, continuous measurement of 100 beats or more, sometimes 15 minutes or more is required, and continuous measurement with an accuracy within 1 msec of the pulse interval is required. Therefore, there is a problem with high-accuracy detection of the individual acceleration pulse wave for each beat and the time position detection accuracy of the a wave.

  As described above, the basis of the heart rate variability measurement in the conventional autonomic nervous activity evaluation is based on the fluctuation of the generation interval of the electrocardiographic pulse that causes the heart beat, in particular, the R wave interval (R -R interval) is measured and evaluated. Various substitutions of this RR interval with other heartbeat detection means are also performed. For example, heart rate or pulse rate is measured by heart sound, carotid artery pressure pulse wave, fingertip volume pulse wave, or the like. In the conventional method, generally, a pulse is generated when a value obtained by converting these beats into an electric signal (generally, a voltage) exceeds a certain level, and the number of beats per minute is counted. There are only.

  However, in order to evaluate the autonomic nervous function that must measure fluctuations of a few percent, it is necessary to measure the interval between individual pulsations with an accuracy of the order of milliseconds. Become.

  The volume pulse wave has a variable base line and is difficult to detect stably. Also, there is no time position accuracy. In some cases, the amplitude of the pulse wave may be very small due to the low temperature or the influence of physical condition. In this case, the S / N (signal / noise) ratio may be small, and the pulse itself may not be detected. Attempts have also been made to detect velocity pulse waves and acceleration pulse waves. However, when the S / N ratio is poor, many noise peaks occur, making it difficult to identify the peaks to be detected.

  Then, there is no problem as long as the measured heartbeat interval matches the RR interval of the electrocardiogram, but this is not necessarily obvious. For example, it may be possible to detect the minimum point or maximum point of the fingertip plethysmogram as the time position of the pulsation, but these are affected by baseline fluctuations and are physiologically affected, such as the drive output of individual heartbeats. Also susceptible to fluctuations. In order to effectively detect an autonomic nerve disorder in which the heart rate variability coefficient to be detected is small and the RR interval of the electrocardiogram is within 1%, at least with an RR interval of the electrocardiogram and an accuracy within a few milliseconds. Must be associated. However, it is difficult to achieve such accuracy with the conventional method.

Also, in practical applications, in order for the output result of automatic analysis by a personal computer to be reliable, when an abnormal a-a interval is detected, a false detection (a peak other than noise or a wave is a). Whether the a-a interval is erroneously measured due to a detection error (when a wave that actually exists is missed) or whether the actual a-a interval is detected. It becomes a problem.
When calculating the average waveform and obtaining only the feature amount of the waveform, it is only necessary to average only those that can be detected by detecting individual pulse waves, but it can detect fluctuations in the continuous aa interval. In order to determine whether the a-a interval is abnormal or normal, it is necessary to dramatically improve the detection accuracy of individual pulse waves. In practice, it is best to display and confirm the measurement waveform and the a-wave detection position at the same time, and no matter how the analysis accuracy of the analysis software is improved, the need for visual confirmation remains. It should be constructed so that false detections and detection mistakes can be eliminated as much as possible.

Hereinafter, detection and analysis of the individual acceleration pulse wave will be described with reference to the flowchart of FIG.
1. Calculation of initial value of standard acceleration pulse wave parameter At the start of measurement, it is necessary to obtain a standard acceleration pulse wave for similarity determination, its parameter, and an initial value of aa interval fluctuation width for aa interval abnormality determination . Therefore, while monitoring the waveform, confirm that there is little fluctuation in the baseline of the volume pulse wave and noise, start measurement, detect the peak, bottom or rise of the volume pulse wave, cut out the pulse wave, and the time interval From this, an aa interval and its fluctuation range are obtained, an average waveform is obtained, and an initial value of the standard acceleration pulse wave and the a wave peak value is obtained therefrom. Alternatively, the same processing is performed after confirming that the velocity pulse wave and the acceleration pulse wave are stable.

Thereafter, the next analysis is performed again from the measurement start time using the standard value calculated above.
2. Extraction of a wave candidate
(1) The maximum point of the measured acceleration pulse wave is obtained, the obtained maximum value is compared with the standard wave height value of the a wave, and a wave candidate that falls within a certain range (for example, 60 to 180%) is determined. If it is less than 60%, noise or e-waves may be detected, and if it exceeds 180%, there is a high possibility of noise.

3. As described above, as an a-wave determination condition for an individual acceleration pulse wave, an integrated value of a difference in pulse height between an individual acceleration pulse wave normalized by the peak value of the a wave and a standard acceleration pulse wave or The similarity is calculated and determined using a multiple (double) integral value.
(1) The waveform of the measured acceleration pulse wave is normalized with the peak value of the a wave of the standard acceleration pulse wave or the intermediate value between the peak value of the a wave and the peak value of the a wave candidate. This normalization is based on the amplitude of the measured acceleration pulse wave: [(c wave value of standard acceleration pulse wave) + q * (c wave value of a wave candidate)] / [(1 + q) * (c wave value of a wave candidate) ] (q is a real value greater than or equal to 0 and is practically about 1).

(2) Measured acceleration pulse wave and standard normalized by the peak value of the a wave by matching the time (t) position of the a wave candidate point of the measured acceleration pulse wave and the a wave of the standard acceleration pulse wave (Ta) Find the difference in height from the acceleration pulse wave.
(3) In the range of Ta-t1 to Ta + t2, the absolute value of the obtained wave height difference is integrated to obtain the similarity. Here, t1 may be set to, for example, 0.1 seconds, and t2 may be set to a time of, for example, an ae interval. If this range is too wide, the difference from the standard waveform in the diastolic phase will become large, such as when the next a wave appears immediately after the e wave due to an arrhythmia such as extrasystole, and the degree of similarity will decrease. Cannot be detected.
In this case, in the range of Ta−t1 to Ta + t2, the absolute value of the integrated wave height difference may be further integrated (double integration) to obtain the similarity.

(4) When the similarity is high, the a-wave candidate is determined as an a-wave. When the degree of similarity is low, the a-wave candidate is not determined as a-wave but is determined as noise, and the a-wave candidate is extracted again.
(5) A time difference between the a wave determined this time and the previous a wave is obtained, and this is calculated as an aa interval Taa.

The grounds for evaluating the degree of similarity using the integral value or the multiple integral value of the above-described acceleration pulse wave height differences are as follows.
(1) In general, acceleration pulse waves are resistant to baseline fluctuations, so that there is an advantage that even if evaluation is performed based on the difference in wave height, they are not affected by baseline fluctuations of volume pulse waves and velocity pulse waves. However, differential waveforms are generally susceptible to high-frequency noise, and spike-shaped noise cannot be dealt with by evaluation based on the difference in wave height.

  (2) Since the integration of the acceleration pulse wave is basically the velocity pulse wave, it is considered that the difference in velocity pulse wave height is used as the similarity. However, in this case, if the baseline fluctuation of the velocity pulse wave is large, a determination error occurs. This is because even if the waveform of the velocity pulse wave is exactly the same, a wave height difference corresponding to the baseline change occurs. On the other hand, the value of the acceleration pulse wave, which is the differential waveform of the velocity pulse wave, is the gradient of the velocity pulse wave waveform, and the integrated value represents a change in the peak value of the velocity pulse wave, and is not affected by baseline fluctuations. Therefore, even if there is a baseline fluctuation in the velocity pulse wave, an integrated value is obtained from the differential waveform (acceleration pulse wave) from which the influence of the fluctuation is removed, and the similarity is calculated and evaluated from this to obtain a stable individual pulse. Waves can be determined.

(3) When spike-like noise cannot be ignored in the velocity pulse wave, the similarity evaluation based on the double integration described in the above item (3) is effective. The modification of the integration for obtaining the similarity is not particularly limited, and in addition to the integration of the absolute value described above, the square of the waveform data may be integrated to calculate the square root thereof.
(4) In addition, in order to solve the above-mentioned problem (the baseline fluctuation is large) when evaluating the degree of similarity using the pulse height difference of the velocity pulse wave, the value obtained by integrating the velocity pulse wave with the pulse cycle is used. It can be corrected as a baseline, but it will not work if there is an arrhythmia.

Next, similarity determination by integration (difference integration) of the above-described acceleration pulse wave difference will be described in detail with reference to FIG. The horizontal axis in FIG. 6 is time (msec), and the vertical axis is the peak value.
At the zero point T (n) of the difference A1-A0 between the measured acceleration pulse wave A1 and the standard acceleration pulse wave A0, the gradient of the velocity pulse wave (standard velocity pulse wave) V0 corresponding to the standard acceleration and the measured acceleration pulse wave The slope of the corresponding velocity pulse wave (measured velocity pulse wave) V1 is the same, and the wave height difference (value of V1-V0) of V1 with respect to V0 at this time is ΔV (n) (in the case of this figure, this Value is negative). The measured acceleration pulse wave rises relative to the standard acceleration pulse wave when the difference A1-A0 is positive, and falls during the negative period. For example, the integral value of the difference A1-A0 in the positive period (period from T (0) to T (1)) represents the increase ΔV (1) −ΔV (0) of the peak value of the velocity pulse wave. The integrated value of A1-A0 in the negative period (period from T (1) to T (2)) represents the decrease ΔV (2) −ΔV (1) of the peak value of the velocity pulse wave.

  In general, the entire level of the velocity pulse wave may change due to baseline fluctuations. In the case shown in FIG. 6, the base line of the measured velocity pulse wave V1 is low. In such a case, a detection error may occur when a pulse is detected by the peak value of the velocity pulse wave. The change in the height difference of the measured velocity pulse wave V1 with respect to the standard velocity pulse wave V0 is not affected by such baseline fluctuation. Therefore, the integral of the absolute value of the difference A1-A0 can be used as a measure of the shape difference of the measured velocity pulse wave V1 with respect to the standard velocity pulse wave V0 without being affected by the baseline fluctuation of the velocity pulse wave.

  However, when evaluating by the difference in wave height, if there is high-frequency noise or pulse-like noise, the evaluation value of similarity deteriorates. This problem can be solved by integrating the difference A1-A0 (not the absolute value) and evaluating the similarity from the integral of the absolute value. In this case, the shape difference of the volume pulse wave is evaluated excluding the influence of the baseline fluctuation.

  Further, when emphasizing the real time property, the order of the third (2) to (4) and the third (5) may be reversed in order to reduce the amount of calculation. In other words, when the time interval between the a-wave candidate and the previous a-wave is in the normal range, it is possible to determine the a-wave without evaluating the similarity and evaluate the similarity only when the a-a interval is abnormal. .

4). Method for Determining Abnormal Value of Aa Interval If an abnormality occurs in the aa interval during measurement, the abnormality is determined as follows.
DTa [n] = Taa [n] −Taa [n−1] of adjacent aa interval Taa, that is, (a−a interval fluctuation) is a certain range (for example, twice the standard deviation Sdv_DTaa of DTaa) With respect to Taa that excludes Taa that is not within ()), a standard aa interval is constituted by these values, and abnormality of the aa interval is determined. This standard a-a interval can use the transition average of data before and after the determination target data. However, when considering real-time characteristics, using the (weighted) average of past data, What is necessary is just to re-determine by the average (weighted) including future data.

  When an algorithm is configured in consideration of real-time characteristics, the aa interval at the time of evaluation is the past average aa interval or the immediately preceding aa interval (standard aa interval). ) As a reference, when the value exceeds a certain reference value (for example, 4 * Sdv_DTaa), the change DTaa of adjacent aa intervals sequentially enters a certain range (for example, 2 * Sdv_DTaa) immediately after that point. Several points may be selected, and the standard aa interval may be updated with these values to determine whether the aa interval is abnormal.

Based on FIG. 7, the flow of the aa interval redetermination process will be described.
(1) The standard a-a interval obtained using data up to t = 0 is St_Taa (before correction). The formula for calculating the standard a-a interval is, for example, a formula for updating with a weighted average (paragraph numbers [0061] and [0062]) described later.
(2) Taa (Taa (1)) at t = 1 is compared with St_Taa (before correction) and determined to be abnormal.
(3) DTaa (2) = Taa (2) −Taa (1) is evaluated, and Taa (2) is used as average value calculation data. As described above, this evaluation is the average value calculation data if the DTaa being evaluated is smaller than the threshold value determined from the standard deviation Sdv_DTaa of the DTaa, and is not included in the average value calculation data if it is larger.

(4) Similarly, DTaa (3), DTaa (4) and DTaa (5) are evaluated, Taa (3) and Taa (4) are excluded from the average value calculation data, and Taa (5) is an average value. Calculated data.
(5) The average value of St_Taa (before correction) and Taa (2) and Taa (5) is obtained and set as St_Taa (after correction).
(6) Compare Taa (1) with St_Taa (after correction), and re-determine that the result once determined as abnormal in (2) is normal.

  FIG. 8 shows the transition of the standard a-a interval when the present algorithm is applied to actually measured data. In the figure, the change in Taa (difference from the previous Taa) is also shown, but as can be seen, the abnormal Taa cannot be determined only by the difference in the previous Taa.

  The change in the heartbeat interval is said to be chaotic or fractal, and is very complicated and difficult to determine with a single criterion. A step-like change as shown in FIG. 8 needs to be included in the analysis data as a normal change.

Problems in applying a single commonly used standard will now be described.
It is conceivable that the normal range is a constant range such as ± 15% (85% to 115%) of the standard aa interval. However, since the variation of the aa interval is large among individuals, In this case, it is possible that a detection error that causes normal fluctuation to be abnormal occurs, and conversely, in the case of a subject whose fluctuation is small, it is possible that a false detection that causes abnormal fluctuation to be normal occurs. It is not preferable.

  When the range of the normal aa interval is determined from the entire distribution of the aa interval on the basis of the average value of the aa interval, unlike the above, there are the following problems. In a slow large fluctuation, for example, when a short Taa within the fluctuation range occurs when Taa is long, a place to be determined as an abnormal aa interval is determined as a normal aa interval (FIG. 9).

  Further, the problem of setting the average value of several beats before and after the aa interval measurement value Taa [n] to be determined as the standard aa interval, that is, the standard aa interval obtained from the transition average. The reason why the abnormality Taa cannot be determined only from the difference from is as follows (FIG. 10).

  When the fluctuation width of the respiratory cycle is small and there is a large slow change, and there is a step-like change exceeding the fluctuation width of the respiratory cycle, the intermediate value before and after the change point becomes the standard aa interval. At this time, if this change is regarded as normal, the limit ThrDDTaa of the normal range needs to be more than half of this step-like change. However, in this case, a single aa interval abnormality that is within this ThrDDTaa cannot be detected.

  Further, as shown in FIG. 10, it may not be necessarily abnormal but may be determined as abnormal.

  FIG. 11 shows a graph in which the standard aa interval obtained above and the standard aa interval obtained by the transition averaging method are compared with respect to the actual measurement data regarding the aa interval abnormal value determination. As is clear from this figure, in transitional averaging, there are cases where normal data is determined to be abnormal data when there is a stepped gap in the data string. It can be avoided.

5. Abnormal data processing
(1) In the statistical analysis (variation analysis) of the aa interval, all the aa intervals determined to be abnormal are excluded and analyzed.
(2) In the spectrum analysis, if it is determined as an extrasystole under the following determination conditions, the analysis is performed with correction. If there is other abnormal data, the analysis section should be divided and analyzed so that abnormal data is not included.

  When the first aa interval of adjacent aa intervals is shorter than the normal aa interval and out of the normal range, the sum of the previous aa interval and the current aa interval is the standard aa When entering a predetermined range (for example, 0.75 to 1.25 or 1.5 to 2.5 times) with reference to 1 or 2 times the interval, it is determined as an extra contraction.

  The predetermined range is preferably determined from the distribution of fluctuations in the difference between adjacent aa intervals. For example, assuming that the standard deviation of the difference between adjacent a-a intervals is Sdv_DTaa, ± n * Sdv_DTaa (the value of n is preferably 4 to 5 in the former case, and preferably about 8 to 10 in the latter case) is within a predetermined range. .

6). Update of standard waveform and standard parameters The difference Taa [n] = Ta [n] −Ta [n−1] between the a-wave Ta [n−1] of the previous measurement and the a-wave Ta [n] of the current measurement is When entering the normal range determined as described above, the standard aa interval (St_Taa), the fluctuation range of the aa interval (Sdv_DTaa), the standard a wave peak value (St_ACCa), and the standard acceleration pulse wave waveform are updated.

  This update is based on, for example, an average value or a weighted average value. The update by weighted average may be performed by the following formula.

St_Taa (current) = ((k−1) * St_Taa (previous) + Taa (normal measured value)) / k
In this case, when k = 1, this corresponds to setting the aa interval of the current measurement as the next standard aa interval.

  For the standard acceleration pulse wave, the waveform of the standard acceleration pulse wave is updated with the previous acceleration pulse wave based on the previous a wave Ta [n−1]. It is not updated when it does not fall within the normal range.

  If the individual acceleration pulse wave is detected and analyzed as described above, it is possible to calculate the estimated coefficient of variation by removing the extra systolic wave and other abnormal values. Separately and clinically useful.

[Standard reference value of variation coefficient of acceleration pulse wave aa interval]
Next, the standard reference value of the variation coefficient of the aa interval of the acceleration pulse wave, the variation coefficient of the aa interval of the diabetic patient, and the value of the autonomic nerve function evaluation by the acceleration pulse wave will be described.

  As shown in FIG. 4, the RR interval of the electrocardiogram coincides with the aa interval of the acceleration pulse wave. Usually, the electrocardiogram is measured in the supine position, while the acceleration pulse wave is measured in the sitting position. In the two postures of the supine position and the sitting position, the state of the autonomic balance is different, so that even the same person may have different variation coefficients. Therefore, the acceleration pulse wave was recorded for 121 minutes for 121 healthy people, and the average value and standard deviation of the coefficient of variation (CVaa%) of the aa interval were calculated by age. The coefficient of variation by age is shown in FIG. Moreover, the range of the standard variation coefficient in each age is shown in FIG. 13 as [average value−standard deviation] to [average value + standard deviation].

  As is clear from FIGS. 12 and 13, the variation coefficient of the aa interval of the acceleration pulse wave decreases with aging, but it can be seen that the standard deviation falls within the same range.

[Coefficient of variation of aa interval in diabetic patients]
About the variation coefficient of the aa space | interval of the said acceleration pulse wave, the diabetic patient and the healthy person were compared. The acceleration pulse wave of 26 diabetic patients was recorded for 2 minutes, and the variation coefficient of the aa interval was calculated as described above. FIG. 14 shows a comparison of the coefficient of variation between a healthy person (Normal) and a diabetic patient (DM). As is clear from FIG. 14, the coefficient of variation of diabetic patients decreased in the 40s and 50s.

[Value of autonomic nervous function evaluation method using acceleration pulse wave]
As described above, the change in the acceleration pulse wave aa interval corresponds to the change in the electrocardiogram RR interval. Therefore, it can be said that the evaluation of the variability of the aa interval of the acceleration pulse wave is equivalent to the evaluation of the heartbeat variability by the electrocardiogram. The variation coefficient of the aa interval of the acceleration pulse wave may be about 0.2 to 1.5 higher depending on the age than the variation coefficient of the RR interval of the electrocardiogram. This is because of the sitting position measurement. It is thought that this is because the influence of breathing is greater than the supine position. Therefore, the variation coefficient of the aa interval can be used for the evaluation of the autonomic nervous function by determining the heart rate variability while referring to the standard reference value according to the age.

  In the above system, continuous measurement for a long time and detection of extra systolic waves are possible. In addition, since this system can calculate the estimated coefficient of variation after removal of extrasystole, there is an advantage that the range of clinical application is widened. Furthermore, the acceleration pulse wave measurement is simpler than the case of an electrocardiogram because it only measures the pulse wave of the fingertip in the sitting position without attaching / detaching clothes. Furthermore, the acceleration pulse wave measuring device is less expensive than the electrocardiograph. Therefore, it can be widely used for prediction of complication risk, determination of therapeutic effect, self-management, etc. in various fields such as diabetes, neuropathy, cerebrovascular disease, coronary artery disease, asthma and menopause.

  The pulse wave sensor for measuring the acceleration pulse wave will be described below.

  A pulse wave sensor that can be used in the present invention is a reflective pulse wave sensor that has a light emitting unit and a light receiving unit, and measures a pulse wave of a subject's finger with the light emitting unit and the light receiving unit, and the waveform is Even if it changes, there will be no restriction | limiting in particular if it can detect a wave, The conventional pulse-wave measuring apparatus can be used. For example, in the pulse wave sensor developed by the present inventors, the light emitting unit is arranged on the downstream side of the arterial blood flow of the finger from the light receiving unit, and the upper surface of the light emitting unit protrudes from the upper surface of the light receiving unit. Arranged so that it protrudes from the floor where the abdomen is placed, and a space for attaching the tip of the finger further downstream of the finger artery blood flow than the light emitting part is provided at the tip of the floor It may be like that. In this case, with this configuration, the adhesion of the finger to the light emitting part is improved, and even if the downstream side of the finger arterial blood flow is compressed, the effect on the pulse wave is greater than when the upstream side is compressed. The pulse wave information can be obtained with high reproducibility. Further, the contact area between the finger and the light emitting part is equal to the area of the upper surface of the light emitting part, and the contact area applied to the finger is small, so that the waveform hardly changes.

  The light emitting part has an upper surface usually about 0.1 to 1.5 mm, preferably about 0.2 to 1.0 mm, more preferably about 0.3 to 0.5 mm from the floor surface on which the abdomen of the finger is placed. You may arrange | position so that it may protrude. When the light emitting unit is arranged in this way, the skin surface of the finger pad is covered from the top surface of the light emitting unit, so that the influence of disturbance light, leakage light, and reflected light on the measurement data can be reduced, and the subject wears the finger. In doing so, there is an advantage that the sensor position is recognized by touching the protruding portion, and the finger can be easily placed at a predetermined position. However, if it is less than 0.1 mm, it is difficult to confirm the sensor position, so that it is difficult to place the fingertip at a predetermined position, and the influence of reflected light on the measurement data increases. In addition, if the thickness exceeds 1.5 mm, the finger skin surface floats from the floor surface, resulting in an unstable wearing state, and waveform deformation is caused by the pressure on the finger when the finger is placed, resulting in poor reproducibility. The pulse wave data to be measured varies, making it difficult to obtain accurate pulse wave information.

  The light receiving unit is preferably arranged such that the upper surface thereof is at the same level as the floor surface on which the abdomen of the finger is placed, or is disposed so as to be lower than the floor surface by a predetermined distance. As a result, the adhesion of the finger to the light emitting portion becomes better.

  A pressing material is attached to the surface facing the floor surface of the space where the finger tip is mounted, and the pressing material presses the upper surface of the finger tip further downstream of the finger artery blood flow than the light emitting part. It is preferable. The subject may consciously and unconsciously put force on the fingertip during pulse wave measurement. In this case, if guidance is given to remove the force, the adhesion to the sensor may deteriorate depending on the shape of the finger of the subject. Noise is generated by small finger movements, both when applying force and when removing force. By providing the pressing material, noise is reduced, the reproducibility of measurement data is increased, and accurate pulse wave information can be obtained.

  As described above, since the pressing part is configured to be limited to a small area on the upper surface of the tip of the finger, it is possible to accurately measure the pulse wave of the finger artery blood flow part upstream of the pressing part with high reproducibility. it can.

  The side surface of the light emitting unit is preferably surrounded by a light shielding wall in order to prevent light emitted from the light emitting unit into the finger from leaking to the outside and to prevent reflected light from the abdominal surface of the finger. .

  The light-emitting part is disposed inside the light-shielding wall having an inner surface reflecting the irradiated light, and the upper end of the light-shielding wall is usually about 0.1 to 1.5 mm, preferably 0, from the floor surface on which the abdomen of the finger is placed. It is preferably configured to protrude about 2 to 1.0 mm, more preferably about 0.3 to 0.5 mm, and the abdomen of the finger is placed on the upper end to cover the entire upper end of the light shielding wall. If the upper end of the light-shielding wall protrudes within this range, the skin surface of the finger pad is covered downward from the upper surface of the light emitting unit, so the influence of disturbance light, leakage light, and reflected light on the measurement data should be reduced. In addition, when the subject wears a finger, there is an advantage that the sensor position is recognized by touching the protruding position of the light shielding wall, and the finger is easily placed at a predetermined position.

  However, if it is less than 0.1 mm, it is difficult to confirm the position of the light-shielding wall, so that it is difficult to place the fingertip at a predetermined position, and the irradiation light from the light emitting part and the reflected light from the finger pad surface easily leak and measurement The effect of reflected light on the data is increased. In addition, if the thickness exceeds 1.5 mm, the finger skin surface floats from the floor surface, resulting in an unstable wearing state, and waveform deformation is caused by the pressure on the finger when the finger is placed, resulting in poor reproducibility. The pulse wave data to be measured varies, making it difficult to obtain accurate pulse wave information.

  It is preferable that the pressure when pressing the upper surface of the tip of the finger with the pressing material is usually 50 to 200 gW, preferably 70 to 150 gW.

  The pulse wave sensor that can be used in the present invention includes a light emitting unit and a light receiving unit, and the light emitting unit is a reflection type pulse wave sensor that measures a pulse wave of a subject's finger using the light emitting unit and the light receiving unit. Is disposed on the downstream side of the arterial blood flow of the finger from the light receiving portion so that the upper surface protrudes from the upper surface of the light receiving portion, and an infrared transmissive window is provided above the light emitting portion and the light receiving portion. A space for placing the upper surface of the window so that it protrudes a predetermined distance from the floor on which the abdomen of the finger is placed, and for attaching the tip of the finger further downstream of the finger artery blood flow than the light emitting part May be provided at the tip of the floor.

  The upper surface of the window part usually protrudes about 0.1 to 1.5 mm, preferably about 0.2 to 1.0 mm, more preferably about 0.3 to 0.5 mm from the floor surface on which the abdomen of the finger is placed. It is preferable to arrange so as to.

  It is preferable that the pressure when pressing the upper surface of the tip of the finger ahead of the window with the pressing material is usually 50 to 200 gW, desirably 70 to 150 gW. If it is less than 50 gW, the amplitude of the pulse wave is small, noise due to vibration during measurement and shaking of the subject's finger is likely to enter, and the measurement waveform is likely to be deformed due to the tension of the subject. Moreover, when it exceeds 200 gW, a measurement waveform will deform | transform extremely. When the entire finger is pressed, the measurement waveform is deformed and the reproducibility is lowered.

  Hereinafter, a pulse wave sensor that can be used in the present invention will be described in detail with reference to the drawings.

  FIG. 15 is a diagram (FIG. 15A) showing a cross-sectional structure of a finger wearing portion which is a main part of the reflection type pulse wave sensor, and an enlarged view showing the vicinity of the light emitting portion and the light receiving portion (FIG. 15B). )), Shown with a finger on.

  This reflection type pulse wave sensor has a light emitting part and a light receiving part, and can measure a pulse wave by wearing a finger of a subject, and an upper part made of an openable and closable synthetic resin constituting a lid part. And a synthetic resin floor portion configured to be able to place the finger pad portion. The upper part may have a shape whose inner surface conforms to the outer shape of the finger, and the floor part has a flat or slightly lower base of the finger to block out disturbance light even if the floor surface is flat. It may be in an inclined shape. As will be described below, a pressure member is provided at the tip of the upper part, and the tip of the finger further downstream from the light emitting part of the arterial blood flow of the finger placed on the floor can be pressed and fixed. In addition, a light emitting portion and a light receiving portion are disposed at predetermined positions on the floor portion. The pressing material may be any material that can press and fix the tip portion of the finger, for example, a cushioning material or a plate material such as a spring material, so that the tip portion of the finger can be pressed with a predetermined pressure. It is configured. The sensor is provided with a current / voltage conversion circuit for reflected light and an amplifier. When this sensor is connected to a personal computer, accurate pulse wave information can be obtained based on the output from the sensor.

  In the case of this pulse wave sensor, when a finger is inserted into the finger wearing part and light such as infrared rays is applied to the abdomen at the tip of the finger, hemoglobin (red blood cells) in the capillary blood vessel absorbs part of the light and reflects light. The amount changes (the amount of light reflected decreases in the part where the amount of blood is large). This subtle change in the amount of reflected light is detected, the detected reflected light is converted from current to voltage, transmitted to an amplifier, and the amplified signal voltage is AD converted using a personal computer and output. Use as pulse wave information.

  As shown in FIGS. 15 (a) and 15 (b), the light-emitting section 1 made of a semiconductor light-emitting element such as a light-emitting diode (LED) is provided on the finger wearing section constituting the main part of the pulse wave sensor. ) Or the like, which is arranged downstream of the arterial blood flow of the finger 3 of the subject from the light receiving unit 2 made of a semiconductor light receiving element. Looking at the path of the irradiation light 1a from the light emitting unit 1 in the finger, the luminous flux in the light emitting part diffuses and spreads as it travels in the finger. For this reason, the light amount change of the light receiving unit 2 due to the change in the amount of incident light from the light emitting unit 1 is large, and the light amount change of the diffused light received by the position change of the light receiving unit 2 is small. Therefore, it is necessary that the light emitting unit 1 is in close contact with the finger. However, improving the adhesion leads to applying extra pressure on the finger. Therefore, in the present invention, the light emitting unit 1 is disposed on the downstream side of the finger artery blood flow from the light receiving unit 2 so that excessive pressure is not applied to the finger.

The light emitting unit 1 is arranged such that the upper surface of the light emitting unit 1 protrudes (ie, becomes higher) than the upper surface of the light receiving unit 2 by a predetermined distance. That is, the height H ₁ of the light emitting unit 1 is configured to be higher than the height H ₂ of the light receiving unit 2 by a predetermined distance. A space 4 is provided further downstream of the finger arterial blood flow than the path of the light 1a emitted from the light emitting unit 1 made of an infrared LED or the like at the distal end portion of the finger mounting portion. It is comprised so that it can be mounted in space.

  The surface on which the finger pad portion of the finger mounting portion is placed is configured as a finger placement floor surface 5. A light emitting unit 1 and a light receiving unit 2 are provided at predetermined positions on the floor surface 5, and the tip portion of the floor surface is inclined and rises, and the tip of the finger is appropriately stored. In this finger wearing part, the pressing material 6 is provided on the surface that is downstream of the arterial blood flow from the position where the light emitting part 1 is disposed and that faces the floor surface. With this pressing material, the tip part (preferably the nail part) of the attached finger is lightly pressed and fixed so that the attached finger does not move. With this configuration, small movements of the subject's conscious and unconscious fingers are reduced, noise generation is reduced, and as a result, changes in the measurement waveform are also reduced. Even if the downstream side of the arterial blood flow is pressed by the pressing material, the influence on the pulse wave is small.

  When the irradiation light 1a from the light emitting unit 1 is reflected from the skin surface of the finger and enters the light receiving unit 2, this reflected light becomes noise, and the amount of light received entering the light receiving unit 2 varies. For this reason, an accurate pulse wave cannot be measured. Moreover, if the irradiation light 1a leaks outside the pulse wave sensor, the efficiency of the irradiation light is reduced, and the amount of reflected light 2a received by the light receiving unit is reduced, making it difficult to measure an accurate pulse wave. Therefore, in the present invention, it is preferable to surround the side surface of the light emitting unit 1 with the light shielding wall 7 in order to prevent excessive reflected light and leakage light.

  The shape of the light shielding wall 7 is not limited as long as it is a shape that eliminates reflected light and leakage light, but for example, a cylindrical shape along the outer peripheral shape of the light emitting unit 1 is preferable. The attached finger is brought into close contact with the upper surface of the light shielding wall at a point 7a and fixed. The light shielding wall 7 may be black on the side of the light receiving unit 2, and the inner surface thereof may be a mirror surface. The material of the light-shielding wall is not particularly limited as long as it has a property of shielding infrared rays. For example, a thermoplastic resin such as polypropylene resin or ABS resin that does not substantially transmit infrared rays, or black coating on these. And the like that have been surface-treated.

  An infrared transparent insulator cap 8 is provided on the upper surface of the light emitting unit 1 so that the light emitting unit 1 and the finger 3 are not in direct contact with each other. This is to prevent the current-carrying part of the light-emitting part from being affected and to prevent the surface of the light-emitting part from being cleaned. The outer shape of the insulator cap 8 may be any shape such as a cylindrical shape along the shape of the upper portion of the light emitter 1. If the upper surface of the insulator cap 8 is formed of a concave lens, the directivity of the emitted light can be further expanded. The material of the insulator cap is not particularly limited as long as it is an infrared transmissive material having high translucency with respect to infrared rays, and examples thereof include acrylic resin, polyethylene resin, polycarbonate resin, and polystyrene resin. Further, it is preferable that the light receiving unit 2 and the finger 3 are in direct contact with each other so that no pressure is applied to the finger so that a gap is provided between the light receiving unit 2 and the finger 3.

  FIG. 16 shows the influence of directivity between the light emitting element of the light emitting unit 1 and the light receiving element of the light receiving unit 2. As shown in FIG. 16A, when the arrangement of the light emitting element of the light emitting unit 1 and the light receiving element of the light receiving unit 2 is a conventional arrangement having strong directivity, if the optical axis of the light emitting diode of the light emitting unit 1 is shifted, The effective detection area is also shifted. However, as shown in FIG. 16 (b), if the light emitting element of the light emitting unit 1 having weak directivity and the light receiving element of the light receiving unit 2 are arranged close to each other as in the present invention, the optical axis of the light emitting diode is adjusted. The displacement of the effective detection area with respect to the displacement is relatively small. Therefore, the obtained pulse wave information is accurate.

  By setting the emission angle (half-value angle) α of the irradiation light from the light emitting unit 1 to usually 50 degrees or more, preferably 50 to 85 degrees, more preferably 50 to 80 degrees, the displacement of the effective detection region is relatively small. Become. If it is less than 50 degrees, the displacement of the effective detection area becomes large, and it becomes difficult to obtain accurate pulse wave data.

  In the pulse wave sensor, the longer the distance between the light emitting unit 1 and the light receiving unit 2 is, the smaller the amplitude of the a wave, which is the waveform of the acceleration pulse wave, and the easier it is to generate a noise component. There is a tendency to grow. Further, the longer this distance is, the more the pulse wave of the finger part affected by the pressure is measured, and the measurement waveform is easily deformed. Therefore, if the distance between the light emitting part and the light receiving part is set to a predetermined distance, for example, usually within 8 mm, preferably within 6 mm, the amplitude of the acceleration pulse wave and the ratio between the b wave and the a wave (b / a) falls within the appropriate range. In this case, the deviation of the optical axis is small, the deviation of the effective detection area is small, and the waveform is difficult to deform. It is to be noted that the arterial blood vessel swells in the finger site upstream of the artery where the distance is outside the above range and b / a is small (absolute value is large), and the blood is congested in the downstream finger site. Thus, b / a is large (the absolute value is small). Further, the lower limit of the distance between the light emitting unit and the light receiving unit is not particularly limited as long as it can be set as desired depending on the physical size of the light emitting unit and the light receiving unit, the size of the pulse wave sensor, and the like. Good. For example, you may set to about 2-3 mm.

  Further, in order to prevent the insulator cap from falling off and improve the handleability of the pulse wave sensor main body, as shown in FIG. 17, a structure may be provided in which a collar portion 14 a is provided in a lower portion of the insulator cap 14. In FIG. 17, 11 is a light emitting part, 11a is irradiation light from the light emitting part, 12 is a light receiving part, 13 is a light shielding wall, and 15 is a finger placement floor. The arrangement positional relationship among the light emitting unit 11, the light receiving unit 12, the light shielding wall 13, the floor surface 15 and the like is the same as that shown in FIG. The materials of the light shielding wall 13 and the insulator cap 14 are the same as the materials of the light shielding wall 7 and the insulator cap 8 shown in FIG. Furthermore, if the upper surface of the insulator cap 14 is formed of a concave lens, the directivity of the emitted light can be further expanded.

  In the pulse wave sensor described above, the light receiving unit is arranged so that the upper surface thereof is at the same height as or below the floor surface of the finger mounting unit so that no pressure is applied to the finger. As a result, the finger portion corresponding to the upper surface position of the light receiving portion having the largest proportion of light incident on the light receiving portion is not compressed. For example, what is necessary is just to arrange | position a light-receiving part so that it may become about 1 mm lower than the finger | toe mounting floor surface of a pulse wave sensor.

  FIG. 18 is a diagram (FIG. 18A) showing a cross-sectional structure of a finger wearing portion, which is a main part of still another reflective pulse wave sensor, and an enlarged view showing the vicinity of a light emitting portion and a light receiving portion (FIG. 18). 18 (b)), which is shown with a finger attached. 18, the same components as those in FIG. 15 are denoted by the same reference numerals. Hereinafter, components different from the case of FIG. 15 will be described.

  According to the embodiment shown in FIGS. 18A and 18B, an infrared transmissive window portion 9 is provided above the light emitting portion 1 and the light receiving portion 2. The window 9 is arranged such that the upper surface thereof is higher than the floor 5 on which the abdomen of the subject's finger is placed by a predetermined distance (0.1 mm or more, for example, about 0.35 mm). As shown in FIG. 18B, the window 9 may be placed and fixed on the edge of the floor so as to cover the light emitting part 1 and the light receiving part 2, or the edge notch There may be no restriction | limiting in the method of arrangement | positioning. By providing the window portion 9, the light emitting portion 1 and the light receiving portion 2 and the subject's finger are prevented from coming into direct contact. As a result, the current-carrying part is not affected, and the surface of the light-emitting part and the light-receiving part need not be wiped off, which makes maintenance easier.

  The outer shape of the window portion 9 is not particularly limited, and may be, for example, a plate shape having a thickness of about 0.5 mm. If the upper surface of the window 9 is formed of a concave lens, the directivity of the emitted light can be further expanded. The material of the window portion is not particularly limited as long as it is an infrared transmissive material having high translucency with respect to infrared rays, and examples thereof include acrylic resin, polyethylene resin, polycarbonate resin, and polystyrene resin.

  According to the pulse wave sensor, the light emitting portion is placed downstream of the light receiving portion in the arterial blood flow of the finger, and the upper surface of the light emitting portion protrudes a predetermined distance from the upper surface of the light receiving portion, and the abdomen of the finger is placed by a predetermined distance. Since the space is provided at the tip of the floor so that the tip of the finger can be mounted further downstream of the finger arterial blood flow than the light emitting part, the finger is placed so as to protrude from the floor. In addition to improving the adhesion to the light-emitting part, even if the downstream side of the finger artery blood flow is compressed, there is less influence on the pulse wave compared to the upstream side being compressed, and accurate pulse wave information with high reproducibility can be obtained. Can be obtained.

  In addition, when an infrared transmissive window is disposed above the light emitting unit and the light receiving unit, the upper surface of the window is disposed so as to protrude a predetermined distance from the floor on which the abdomen of the finger is placed. The pulse waveform information can be obtained with high reproducibility and little influence on the measurement waveform.

  Hereinafter, the technique related to the autonomous nerve function evaluation apparatus of the present invention will be described.

  The pulse wave analysis method used in the autonomous nerve function evaluation apparatus of the present invention is a pulse wave analysis method for obtaining information corresponding to fluctuations in the RR interval of an electrocardiogram from a pulse wave of a living body, and continuously for a predetermined time. An acceleration pulse wave is calculated by second-order differentiation of the measured pulse wave waveform, an aa interval is obtained from a continuous waveform of the acceleration pulse wave, and a variation in the aa interval is calculated as an RR interval of the electrocardiogram. The interval corresponds to the fluctuation.

  The pulse wave analysis method is also a pulse wave analysis method for obtaining information corresponding to a change in the RR interval of an electrocardiogram from a pulse wave of a living body, and includes a past acceleration pulse wave, preferably a past several to several tens of beats. The standard acceleration pulse wave obtained from the acceleration pulse wave is determined as the standard acceleration pulse wave, and the similarity between the standard acceleration pulse wave and the measured acceleration pulse wave is evaluated to determine the individual acceleration pulse wave. The aa interval is obtained from the continuous waveform of the individual acceleration pulse wave, and the variation of the aa interval is set as an interval corresponding to the variation of the RR interval of the electrocardiogram.

  Evaluation of the similarity of the above waveform is performed using a waveform normalized so that the peak value of the a-wave candidate of the measured acceleration pulse wave is equal to or intermediate between the peak values of the a-wave candidate of the standard acceleration pulse wave In addition, the time positions of the a wave of the standard acceleration pulse wave and the a wave candidate of the measurement acceleration pulse wave are matched, and the difference between the standardized measurement acceleration pulse wave and the standard acceleration pulse wave is obtained.

  The evaluation of the similarity between the waveforms is an a-wave determination condition for the individual acceleration pulse wave, and the measured acceleration pulse wave is an intermediate value or a wave wave between the peak value of the a-wave candidate and the a-wave peak value of the standard acceleration pulse wave. This is based on the similarity calculated using the integral value or the multiple integral value of the pulse height difference between the individual acceleration pulse wave normalized by the high value and the standard acceleration pulse wave.

  In the pulse wave analysis method described above, the standard aa interval is configured by these values with respect to the aa interval excluding those in which the change in the adjacent aa interval is outside a certain range, and the aa interval is abnormal. It consists of judging.

  As the standard a-a interval, an average of past data or a weighted average is used, and data that has been determined to be abnormal is re-determined with an average including future data or a weighted average. Hereinafter, “average or weighted average” may be simply referred to as “(weighted) average”.

  In the pulse wave analysis method, the aa interval at the time of evaluation is a past average aa interval, or a weighted transition average in which the weight of past aa interval data is larger than the future, Or, when a certain reference value is exceeded with reference to the immediately preceding aa interval, several points are selected from the immediately following point in time so that changes in adjacent aa intervals fall within a certain range. The standard aa interval is updated to determine whether the aa interval is abnormal.

  In the above-described pulse wave analysis method, a pulse wave of a living body is a reflection type pulse wave sensor having a light emitting part and a light receiving part, and the light emitting part is located downstream of the light receiving part in the arterial blood flow of the finger, and the upper surface thereof It is arranged so that it protrudes from the upper surface of the light receiving part and protrudes from the floor where the abdomen of the finger is placed by a predetermined distance, and the tip of the finger is attached further downstream of the finger artery blood flow than the light emitting part The measurement is performed by attaching a fingertip to a pulse wave sensor in which a space for performing this is provided at the tip of the floor surface.

  The pulse wave measurement is carried out using a pulse wave sensor in which the light emitting part is arranged such that the light emitting part of the pulse wave sensor protrudes 0.1 to 1.5 mm above the floor surface on which the abdomen of the finger is placed. Done with.

  The pulse wave measurement is performed so that the upper surface of the light receiving unit of the pulse wave sensor is at the same level as or lower than the upper surface of the light emitting unit, and is lower than the floor surface by a predetermined distance. This is performed using a pulse wave sensor that is arranged.

  In the measurement of the pulse wave, a pressure member is attached to a surface facing the floor surface of the space where the tip of the finger of the pulse wave sensor is attached, and this pressure member is further downstream of the finger artery blood flow than the light emitting portion. This is performed using a pulse wave sensor configured to hold the upper surface of the tip of the finger.

  The pressing material is configured to press the upper surface of the tip of the finger further downstream of the finger artery blood flow with the pressure of 50 to 200 gW with the pressing material.

  In the measurement of the pulse wave, the side surface of the light emitting part of the pulse wave sensor is surrounded by a light shielding wall whose inner surface has a reflection characteristic for irradiation light, and the upper end of the light shielding wall is 0.1 from the floor surface on which the abdomen of the finger is placed. It is performed using a pulse wave sensor configured to protrude by ~ 1.5 mm.

  In the measurement of the pulse wave, an infrared transmissive window is provided above the light emitting part and the light receiving part of the pulse wave sensor so that the upper surface of the window protrudes a predetermined distance from the floor on which the abdomen of the finger is placed. It is performed using the said pulse wave sensor arrange | positioned in this.

  It arrange | positions so that the upper surface of the said window part may protrude 0.1-0.5 mm from the floor surface which mounts the abdominal part of a finger | toe.

  The autonomic nervous function evaluation method is based on the pulse wave analysis method described above. For consecutive aa intervals, the first aa interval of adjacent aa intervals deviates from the normal range from the standard aa interval. A predetermined case in which the sum of the previous aa interval and the current aa interval is determined from the distribution of fluctuations in the aa interval on the basis of 1 or 2 times the standard aa interval. When entering the range, it is determined to be an extrasystole.

  This autonomic nervous function evaluation method is also a method for evaluating autonomic nervous function based on the statistic of the aa interval. If the aa interval is outside the normal range based on the pulse wave analysis method, And the statistic of the aa interval is calculated, and the autonomic nervous function is evaluated based on the statistic.

  This autonomic nervous function evaluation method is also a method of evaluating the autonomic nervous function by performing frequency analysis of temporal fluctuations of the aa interval, and for the adjacent aa intervals, the first aa interval is the above pulse. Based on the wave analysis method, when the normal aa interval is shorter than the normal range, and the sum of the first aa interval and the next aa interval is one time the standard aa interval or When entering a predetermined range (for example, 0.75 to 1.25 or 1.5 to 2.5 times) based on 2 times, if 1 time is used as a reference, the first a-a interval is set to The correction is made to the sum of both the first aa interval and the next aa interval to delete the next aa interval. It is characterized in that the autonomic nervous function is evaluated by correcting the interval to one half of the sum of both and performing frequency analysis.

  In the autonomic nervous function evaluation method, the autonomic nervous function is evaluated by evaluating the variability of the aa interval while referring to the standard reference values for each age.

  In the autonomic nervous function evaluation method, diabetes is obtained by performing continuous measurement for a long time or detecting an extrasystole wave based on the pulse wave analysis method, and calculating an estimated coefficient of variation after the extrasystole removal. Including neuropathy, cerebrovascular disease, coronary artery disease, asthma, climacteric disorder, etc., it is characterized by predicting complication risk, determining treatment effect, and managing self-health.

DESCRIPTION OF SYMBOLS 1 Light-emitting part 2 Light-receiving part 2a Reflected light H ₁ Height of light-emitting part H ₂ Height of light-receiving part 3 Finger 4 Space 5 Finger mounting floor surface
6 Pressing material 7 Light-shielding wall 7a Contact point between finger and light-shielding wall 9 Window 15 Finger placement floor surface α Emitting angle (half-value angle) of irradiation light

Claims (1)

  Pulse wave measuring means for detecting a pulse wave of a living body and outputting a signal corresponding to the magnitude of the pulse wave, and an acceleration pulse calculated by second-order differentiation of the waveform of the pulse wave obtained by the pulse wave measuring means Waveform parameter analyzing means for analyzing the waveform parameter from the waveform of the wave, and the waveform parameter analyzing means secondarily differentiates the pulse wave waveform measured continuously for a predetermined time to calculate the acceleration pulse wave And means for obtaining a change in the aa interval corresponding to the change in the RR interval of the electrocardiogram from the continuous waveform of the acceleration pulse wave, and further, the change in the adjacent aa interval is within a certain range. Autonomous by fluctuation analysis of acceleration pulse wave, characterized in that a standard aa interval is constituted by these values for an aa interval excluding those that deviate, and an abnormality of the aa interval is determined. Neural function evaluation device.

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